The best security method for employees who use their own devices for work is to keep the device software updated. Regular software updates include security patches that address vulnerabilities, reducing the risk of exploits. This preventative measure is crucial for maintaining the security integrity of not only the individual devices but also the corporate network they connect to.
Reference: Mobile and device security, including the importance of software updates, is covered in CompTIA IT Fundamentals, highlighting the best practices for securing devices used in a corporate environment.